Online Multi-Target Laser Ranging Using Waveform Decomposition on FPGA

Abstract

To achieve online multi-target laser ranging in full-waveform light detection and ranging (LiDAR), a multi-target laser ranging method using waveform decomposition is proposed and implemented on a field programmable gate array (FPGA). In this method, an emitted laser pulse and the laser echo scattered from multiple targets are decomposed into a set of Gaussian functions, then the distances between the LiDAR and the targets are obtained using the waveform parameters of Gaussian functions. The waveform decomposition method is modified and implemented on a FPGA for online laser ranging. Simulations and experiments were conducted to verify the ranging performances of the proposed method by the comparition with those of a post-processing Gauss-Newton (post-GN) method. The results of simulations show that the proposed method is more efficient compared with the post-GN method. The time cost reduces 79.8% to 91.1% for a laser echo scattered from three close targets. In experiments, a lab-built full-waveform LiDAR system was used to obtain the waveforms of emitted laser pulses and laser echoes scattered from 1, 2, or 3 targets. The results show that the ranging performances of the proposed method are comparable with those of the post-GN method. The proposed method is capable to distinguish close targets with an equivalent time space of 1.8 times pulse width of an emitted laser pulse and decompose laser echo with a signal-to-noise ratio (SNR) higher than 20 dB. The results show that the proposed method can obtain distances of multiple close targets from a laser echo efficiently and accurately.